Method and apparatus for making interconnected bags having closure flaps and bottom gussets

ABSTRACT

Continuous web of heat-sealable material having J-shaped crosssectional shape advanced over a bar having an angular slot. Lip of wider ply of the material guided through slot to fold lip back against outer face of wider ply. As material passes over outer faces of two spaced-apart support plates, an intermediate plate pushes folded edge into region between the support plates to form a gusset. Material then provided with pairs of closely spaced seal lines, and line of perforations between each pair of seal lines.

United States Patent [72] Inventor William Guenther Hicksville, N.Y.[21] Appl. No. 810,432 [22] Filed Jan. 23, 1969 Division'of Ser. No.673,726,:Oct. 9, 1967,!fatent No. 3,469,769. [45] Patented Jan. 5, 1971[73] Assignee Lion Packaging Products Company, Inc.

a corporation of New York [54] METHOD AND APPARATUS FOR MAKINGINTERCONNECTED BAGS HAVING CLOSURE FLAPS AND BOTTOM GUSSETS 3 Claims, 10Drawing Figs.

[52] U.S.Cl 93/8, 93/35 [51] lnt.Cl B3lb 1/00 [50] Field ofSearch 93/35,8

[56] References Cited UNITED STATES PATENTS 3,147,674 9/1964 Hoeppner93/35 3,194,124 7/1965 Warp Primary Examiner-Bernard StickneyAttorney-Breitenfeld & Levine ABSTRACT: Continuous web of heat-scalablematerial having .l-shaped cross-sectional shape advanced over a barhaving an angular slot. Lip of wider ply of the' material guided throughslot to fold lip back against outer face of wider ply. As materialpasses over outer faces of two spaced-apart support plates, anintermediate plate pushes folded edge into region between the supportplates to form a gusset. Material then provided with pairs of closelyspaced seal lines, and line of perforations between each pair of seallines.

PATENTED JAN SIS?! SHEET 1 BF 2 m wt in ATTORNEY5 F a %N\ um. AQ \m\ \wM 7 m m T w\ H A f N u w% l H @mm 7 v Q mN W METHOD AND APPARATUS FORMAKING INTERCONNECTED BAGS HAVING CLOSURE FLAPS AND BOTTOM GUSSETS Thisapplication is a division of copending application, Ser. No. 673,726,filed Oct. 9, 1967, now US. Pat. No. 3,469,769, issued Sept. 30, 1969.

This invention relates to a method and apparatus for making plastic bagsof the type formed by two flat rectangular walls joined along threesides and open along the fourth side to define a filling opening.

Flat plastic bags of this type have in recent years gained wideacceptance, and are merchandised primarily for household use. Such bagsare shown, for example, in US. Pat. Nos. 3,098,594 and 3,173,601. Thesebags are usually made, on a mass production basis, from a continuousflattened tube of relatively thin gage plastic material. The tube isprovided with transverse heat seal lines spaced apart along its length,each seal line joining the superposed fiat walls of the tube anddefining the bottom of one bag. Close and parallel to each seal line thetube walls are perforated or slit to define weakened tear lines. In thiscondition a length of the flattened tube, representing a quantity ofinterconnected bags, may be wound on a rigid core and packed in a box.When a bag is needed, the endmost bag is unwound from the core and tornfrom the next adjacent bag. The bag will be closed along three sides,but open along the fourth side created by the newly torn edge.

Bags of this type serve satisfactorily for many uses, but they dopresent certain problems. First, they cannot readily be closed.Customarily, short pieces of paper-covered wire are sold with such bags,the wire being twisted around the gathered open end portion of the bagto close it. This procedure is obviously cumbersome. Furthermore, suchbags suffer from being two dimensional, i.e., their walls lie incontiguous planes with their edges joined. Hence, the ratio between theholding capacity of these bags and their flat area is relatively small.Solutions to both of these problems are illustrated in US. Pat. Nos.2,709,467 and 2,842,179, wherein plastic bags are shown having closureflaps and bottom gussets. However, the bags of these patents must bemade individually, i.e., they cannot be made in an interconnectedseries, as described above. Consequently, the convenience of a roll ofsuch bags which can be separated one by one, as needed, is notavailable.

It is an object of the present invention to provide a method andapparatus for producing a series of interconnected yet readily separableplastic bags having closure flaps and expandable gussets.

To accomplish these objectives, the invention contemplates starting witha continuous length of heat-sealable sheet material longitudinallyfolded to yield a .I-shaped cross-sectional shape. The material isadvanced longitudinally, and during this advancement the lip of thewider ply is guided through an angular slot in a bar over which thematerial passes, whereby the lip is folded back upon the outer face ofthe wider ply. Thereafter, as the plies pass over the outer surfaces oftwo spaced-apart support plates, an intermediate plate pushes the foldededge between the two plies into the region between the plies. In thiscondition, the material is provided with pairs of closely spacedtransverse heat seal lines, the seals serving to fuse together the twoplies, to define the opposed side edges of two adjacent bags, the foldedback lip, to define a closure flap secured at its ends to the bag sides,and the pushed-in folded edge, to define a bottom gusset for each bagalso secured at its ends to the bag sides. Finally, a line ofperforations or slits is provided between each pair of seal lines todefine a weakened tear line separating adjacent bags.

Additional objects and advantages of the invention will be apparent fromthe following description in which reference is made to the accompanyingdrawings.

In the drawings:

FIG. 1 is a face view of an individual bag according to this inventionafter it has been detached from the remaining bags of its series;

FIGS. 2 and 3 are cross-sectional views taken on lines 2-2 and 3-3,respectively, of FIG. 1;

FIG. 4 is a face view of interconnected bags according to thisinvention;

FIG. 5 is a cross-sectional view taken on line S-of FIG. 4;

FIG. 6 is a schematic view of a bagmaking apparatus according to thisinvention; and

FIGS. 7, 8, 9, and 10 are cross-sectional views taken at various pointsalong the length of the bag material as it moves the apparatus of FIG.6.

At the outset, it should be mentioned that the thickness of the bagmaterial has been exaggerated for the sake of clarity in FIGS. 2, 3, 5,and 7-10. The material employed is preferably thin heat-sealablematerial such as polyethylene sheeting.

A series of interconnected, but readily separable, bags is shown in FIG.4, the adjacent bags being separated by transverse lines of slits 16(see also FIG. 5). The slits 16 constitute lines of weakness betweenadjacent bags along which the bag material may easily be torn toseparate the bags 15. Thus, to obtain an individual bag, as shown inFIG. 1, the bag material is torn along the line of slits 16 between theendmost bag in the series and the next successive bag.

Each bag is formed by two superposed plies or walls 17 and 18 fusedtogether along their side edges by heat seal lines 19 and 20. As will bedescribed below, each pair of relatively closely spaced seal lines 19and 20 (see FIG. 4) is formed simultaneously, but the relatively largedistance between each two successive seal lines 20 and 19 defines thewidth of an individual bag 15. Each line of slits 16 is located in therelatively small spacing between each pair of seal lines 19 and 20.

Joined to the upper edge of the bag wall 17, by a fold line 23, is aflap 24. The regions near the end edges of the flap are fused to theplies 17 and 18 at the seal lines 19 and 20. The bag is formed, andsupplied to the consumer with the flap 24 lying against the outer faceof the bag wall 17, as shown in solid lines in FIG. 2. After the bag isfilled, through the open mouth defined by the fold edge 23 and the freeupper edge 25 of the bag wall 18, the bag may be closed by turning theflap 24 over the bag mouth into the position shown in dot-dash lines inFIG. 2. Manipulation of the flap 24 in this way is permitted, despitethe fact that the ends of the flap are secured to the bag walls, by theflexibility of the bag material.

The bottom edges of the bag walls 17 and 18 are joined by two plies 26and 27 (FIG. 2) defining a gusset. The plies 26 and 27 are joined alongtheir inner edges by a fold line 28. The plies 26 and 27 are joined byfold lines along their outer edges to the lower edges of the bag walls17 and 18, respectively. The regions near the ends of the plies 26 and27 are fused to the bag walls 17 and 18 at the seal lines 19 and 20.Thus, the gusset 26, 27 is normally maintained in flattened conditionbetween the bag walls 17 and 18. However, when the bag is filled, theplies 26 and 27 can swing away from each other to enlarge the volume ofthe bag.

The manner in which the series of bags 15 shown in FIGS. 1- -5 may beproduced is illustrated in FIGS. 6-10. A supply roll 31 of so-called.l-stock is provided. This supply is a web of heat sealable materialfolded along an offcenter longitudinal line 32 (see FIG. 7) parallel tothe edges of the web to form a relatively wide ply 17 and a relativelynarrow ply 18, the plies being in superposed relation. Before operationof the apparatus is initiated, the J-shaped web is threaded through themachine. The web is drawn around guide rollers 34 and a slotted bar 35,the latter being supported at its ends by a bracket 36 secured to themachine frame (not shown). The lip 24 of the wider ply 17, which extendsbeyond the free edge 25 of the narrower ply 18, is turned back towardthe outer face of the ply 17 and slipped into a slot 37 (see FIG. 8) inthe bar 35. The slot 37 is arranged at an acute angle to the plane ofthe web so that the slotted bar serves to continuously fold the lip 24back toward the outer face of the ply 17 as the web is continuouslyadvanced.

After leaving the bar 35, the web travels to a roller 40 in the regionof which the folding of the lip 24 against the ply 17 is completed (FIG.9), so that the ply 24 now constitutes a flap. From the roller 40, theplies 17 and 18 are guided around the outer faces of two parallel,spaced-apart, rigid support plates 41 (see FIG. A third intermediateplate 42 extends part way into the space between the plates 41. Theregion of the web adjacent to the fold line 32 (FIG. 7) is threadedbetween the margins of the plates 41 and 42 in a sinuous fashion to formthe gusset plies 26 and 27 and the fold line 28, the latter being thefold line 32 reversed.

After leaving the plates 41 and 42,'the web travels to a roller 43, atwhich the gusset plies 26 and 27 and the bag wheels walls 17 and 18 areflattened against each other, and then to a heat sealing stationcomprising a heat sealing device 44 and a platen roller 45. The heatsealer 44 reciprocates, as indicated by the double-headed arrow, towardand away from the platen roller 45, and is provided with two parallel,spaced apart sealing edges 46 and 47. Thus, each time the heat sealer 44strikes the platen roller 45, with the bag material between them, a pairof relatively close seal lines '19 and are formed by the sealing edges46 and 47, respectively. The reciprocation rate of the heat sealer 44 isrelated to the speed of advancement of the web so that lengths of theweb equal to the desired width of the bags pass between the heat sealerand platen roller during the intervals between successive engagements ofthe heat sealer and platen roller. Any appropriate tensioning means (notshown) for the web to permit instantaneous halting of the web at theheat sealing station without interfering with the continuous webadvancement maybe employed.

From the sealing station, the web moves around a guide roller 50 to acutting station comprising a rotating knife 51 and a stationary platen52. The cutting edge of the knife is serrated, so that only shortunconnected regions of the cutting edge contact the platen 52. The kniferotates in the direction indicated by the arrow at a speed related tothe speed of advancement of the web. in this way, the knife 51 is causedto contact the platen 52 with the web between them only when therelatively narrow region of the web between the seal lines 19 and 20 isbetween them. The serrated edge of the knife thereby produces a line ofslits 16 serving as the tear lines between adjacent bags.

The completed series of interconnected bags is then wound on a takeuproll 53 with the aid of a pressure roll 54. Rotation of thetakeup roll53,'by means not shown, serves to advance the web in a longitudinaldirection through the apparatus. After operation of the apparatus hasbeen terminated, either because of depletion of the supply roll 31 orfor some other reason, the bags on the takeup roll 53may bejrewound orrigid cores (not shown) in suitable bearing bags packed in boxes.

The invention has been shown and described quantities, and the c0resuchlimitations are included in the appended claims.

I claim:

1. A method of making a series of interconnected separable bagscomprising the steps of providing a continuous web of heat sealablesheet material folded along an offcenter longitudinal line to define twosuperposed plies one of which' is beyond the free edge of the narrowerto said offcenter fold line into the region between said plies to form afour ply portion along the other longitudinal edge "off the web,intermittently heat sealing together all of said web plies along pair ofspaced-apart transverse lines, and partially severing all of said pliesalong a line located between each pair of seal lines.

2. A method as defined in claim 1 including the final stepof roging'upsaid interconnected bags on to a core.

pparatus for producing a series of interconnected bu separable bagscomprising means for longitudinally advancing a continuous web of heatsealable sheet material folded along an offcenter longitudinal line todefine two superposed plies one of which is widertha'n ,theother, thewider ply having a-lip extending beyond the free edge of the narrowerply, a bar over which said webis drawn with the wider ply contacting'thebar,

said bar having a slot arranged at an acute angle to, the web as itmoves over the bar, said slot accommodatingthe lip of the web andserving to turn it back toward the outer face of the wider web ply toform a flap, a pair of spaced-apart support plates, each ply slidingover the outer face of one of said plates, an intermediate plate betweensaid support plates for pushing a central'region of the web into thespace between the support plates to form a gusset, a heat sealer forintermittently applying to themoving web two spaced-apart seal linestransverse to the direction of web advancement, and a knife forpartially severing the web between-each pair of seal lines.

in preferredw form only, and by way of example, and may variations maymade in the invention which will still be comprised withinjtjs Y spirit.It is understood, therefore, that, the invention is ntjt. limited manyspecific form or-embodiment except insofar as.

1. A method of making a series of interconnected but separable bagscomprising the steps of providing a continuous web of heat sealablesheet material folded along an offcenter longitudinal line to define twosuperposed plies one of which is wider then the other, the wider plyhaving a lip extending beyond the free edge of the narrower ply,advancing the web longitudinally, continuously folding said lip awayfrom said narrower ply and against the outer face of said wider ply toform a three ply region along one longitudinal edge of the web,continuously introducing longitudinal portions adjacent to saidoffcenter fold line into the region between said plies to form a fourply portion along the other longitudinal edge of the web, intermittentlyheat sealing together all of said web plies along pair of spaced-aparttransverse lines, and partially severing all of said plies along a linelocated between each pair of seal lines.
 2. A method as defined in claim1 including the final step of rolling up said interconnected bags on toa core.
 3. Apparatus for producing a series of interconnected butseparable bags comprising means for longitudinally advancing acontinuous web of heat sealable sheet material folded along an offcenterlongitudinal line to define two superposed plies one of which is widerthan the other, the wider ply having a lip extending beyond the freeedge of the narrower ply, a bar over which said web is drawn with thewider ply contacting the bar, said bar having a slot arranged at anacute angle to the web as it moves over the bar, said slot accommodatingthe lip of the web and serving to turn it back toward the outer face ofthe wider web ply to form a flap, a pair of spaced-apart support plates,each ply sliding over the outer face of one of said plates, anintermediate plate between said support plates for pushing a centralregion of the web into the space between the support plates to form agusset, a heat sealer for intermittently applying to the moving web twospaced-apart seal lines transverse to the direction of web advancement,and a knife for partially severing the web between each pair of seallines.